diff --git a/services/zc/app/requirements.txt b/services/zc/app/requirements.txt
index 657b2d4..13a89e5 100644
--- a/services/zc/app/requirements.txt
+++ b/services/zc/app/requirements.txt
@@ -29,7 +29,7 @@ python-multipart>=0.0.9
 pytest>=8.2.0
 pytest-asyncio>=0.23.0
 pytest-cov>=5.0.0
-httpx>=0.27.0
+httpx>=0.28.1
 
 ## Development
 ruff>=0.4.0
diff --git a/services/zc/requirements-enterprise.txt b/services/zc/requirements-enterprise.txt
index 00a5b93..6e2713c 100644
--- a/services/zc/requirements-enterprise.txt
+++ b/services/zc/requirements-enterprise.txt
@@ -57,7 +57,7 @@ pydantic-settings>=2.5.0
 # === Testing ===
 pytest>=8.3.0
 pytest-asyncio>=0.24.0
-httpx>=0.27.0
+httpx>=0.28.1
 
 # === Development Tools ===
 black>=24.8.0
diff --git a/services/zc/webapp/requirements-web.txt b/services/zc/webapp/requirements-web.txt
index b13e443..210949f 100644
--- a/services/zc/webapp/requirements-web.txt
+++ b/services/zc/webapp/requirements-web.txt
@@ -6,4 +6,4 @@ fastapi>=0.115.0
 uvicorn[standard]>=0.30.0
 # Required by fastapi.testclient.TestClient (tests/test_webapp_server.py);
 # not a transitive dependency of fastapi or uvicorn[standard] on their own.
-httpx>=0.27.0
+httpx>=0.28.1